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UIScrollView的分页效果,以及Masonry在UIScrollView中的用法

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UIScrollView的分页效果,以及Masonry在UIScrollView中的用法

1.Masonry是基于AutoLayout的高度封装

要是你直接用官方的AutoLayout来布局的话，看看下面的代码感受一下

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UIView *view = UIView.new;
view.backgroundColor = [UIColor purpleColor];
view.translatesAutoresizingMaskIntoConstraints = NO;//键值将Autoresizing转换为Constraints
[self addSubview:view];
    
NSLayoutConstraint *width = [NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:0.0 constant:150];
[view addConstraint:width];
    
NSLayoutConstraint *height = [NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:0.0 constant:150];
[view addConstraint:height];
    
NSLayoutConstraint *left = [NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeLeft relatedBy:NSLayoutRelationEqual toItem:view.superview attribute:NSLayoutAttributeLeft multiplier:1.0 constant:100];
[view.superview addConstraint:left];
    
NSLayoutConstraint *top = [NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:view.superview attribute:NSLayoutAttributeTop multiplier:1.0 constant:10];
[view.superview addConstraint:top];

2.所以还是乖乖的用Masonry吧 ：）

创建一个UIScrollView以便测试

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UIScrollView *sc = [[UIScrollView alloc]init];
sc.backgroundColor = [UIColor orangeColor];
//    sc.bounces = NO;//禁止回弹效果
sc.delegate = self;
[self addSubview:sc];
[sc mas_makeConstraints:^(MASConstraintMaker *make) {
   make.left.bottom.right.mas_equalTo(0);
   make.width.equalTo(self);
   make.height.mas_equalTo(200);
}];
    
UIView *lastView;;
for (int i = 0; i < [self randomColor].count; i ++) {
   UIView *view = [[UIView alloc]init];
   view.backgroundColor = [self randomColor][i];
   [sc addSubview:view];
   [view mas_makeConstraints:^(MASConstraintMaker *make) {
       make.top.bottom.mas_equalTo(0);
       make.width.height.equalTo(sc);
//            if (lastView) {
//                make.left.mas_equalTo(lastView.mas_right).offset(0);
//            }else{
//                make.left.mas_equalTo(sc).offset(0);
//            }
       
       make.left.mas_equalTo(lastView ? lastView.mas_right : sc).offset(0);
       
   }];
   lastView = view;
}
[lastView mas_makeConstraints:^(MASConstraintMaker *make) {
   make.right.mas_equalTo(sc).offset(0);
}];

3.遵守其代理方法

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- (NSArray *)randomColor{
    NSArray *colors = [NSArray arrayWithObjects:[UIColor redColor],[UIColor greenColor],[UIColor blueColor],[UIColor grayColor], nil];
//    int number = arc4random() % colors.count;
//    return colors[number];
    return colors;
}


//分页效果
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate{
    if (!decelerate) {
        [self customPage:scrollView];
    }
}

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{
    [self customPage:scrollView];
}


- (void)customPage:(UIScrollView *)sc{
    CGFloat contentOffset = sc.contentOffset.x;

    NSInteger index = (contentOffset + sc.frame.size.width) / self.frame.size.width - 0.5; //-0.5的目的就是为了当刚好没有划到一半时，自动划过去

    [sc setContentOffset:CGPointMake(index * self.frame.size.width, 0) animated:YES];
}